Connectivity to our AWS RDS SQL Server instance has failed today - urgent!

Amazon RDS DB connections can drop for various reasons, assuming this wasn't a maintenance window can be for the following events: a) Client timeout parameters configured at the application end b) Unplanned DB restart/failover c) Server timeout parameters configured in the custom parameter group attached to Amazon RDS. A transient network issue affects the underlying host of your DB Instance. The internal monitoring system detects this issue and proactively initiates recovery for a Single-AZ deployment and failover for Multi-AZ deployments.

To chase for the root cause you need to check the following loss and metrics: 1) Amazon RDS events (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ListEvents.html), 2) CloudWatch metrics (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/monitoring-cloudwatch.html#metrics_dimensions), Enhanced monitoring (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_Monitoring.OS.Enabling.html), 4) Performance insights (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PerfInsights.html) or 5) RDS Database logs (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_LogAccess.html).